The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Short-bowel syndrome (SBS) is a devastating disease associated with mortality rates exceeding 30%. It is a condition where the small intestinal length is far less than required for proper nutrient absorption. This condition can occur in pediatric and adult populations, and may be due to congenital processes, or acquired through the loss of large amounts of small intestine due to inflammatory conditions or ischemic events. The syndrome prevents a self-sustaining absorption of nutrients from the intestine, and supplemental parenteral nutrition is required. An estimated 40,000 patients with intestinal dysfunction from small bowel syndrome require parenteral nutrition. Several long-term effects due to parenteral nutrition have been found to be harmful, such as sepsis, liver disease, and bowel bacterial overgrowth; therefore, this method can only be used as a short-term solution. Care for small bowel syndrome patients is in excess of $200,000 per patient per year, and estimated costs in the United States have exceeded $1 billion yearly.
A number of treatment procedures have been proposed to alleviate small bowel syndrome. Some have tried using growth hormones along with specific nutrients known to stimulate bowel tissue growth. This approach has limited effectiveness and several obstacles, including reversal of the adaptive process after termination of the hormones, lack of somatic muscle growth, and concerns about uncontrolled and tumorous growth.
Another option is to surgically modify the organs to achieve an increase in intestinal length. With this approach, there is a risk of injury to the mesenteric vasculature, leakage of enteric contents due to a very long surgical connection, and the procedures can only be done if the intestine is overly dilated. Despite success in some patients, there is a very high failure rate up to 45% in some series.
Finally, small bowel transplantation has been used for adults and children when other treatments have failed. Although a viable option, transplantation is very costly. Patients require long-term immunosuppression and are at risk for infection and graft failure. Although early patient and graft survival are excellent, five-year graft survival is typically at the 50% level, and patient survival is approximately 60%. Clearly, there is a great need for an alternative procedure to treat short bowel syndrome.
Recently, the principles of the present teachings have demonstrated that mechanical forces can be powerful regulators of tissue growth or regeneration. Through the process of mechanotransduction—the translation of mechanical signals to biochemical ones which affect cell function—the response to the forces results in a cascade of actions which includes the activation of growth mechanisms. Numerous organs have been shown to be mechanoresponsive including bone, lung, and neural tissue. According to the principles of the present teachings, the controlled mechanical stimulation to the small intestine, such as through mechanotransduction of forces applied in a linear fashion to small bowel, can help induce intestinal growth.
According to the principles of the present teachings, implantable bowel extenders are provided that can be used to overcome the issues associated with small bowel syndrome. In some embodiments, the implantable bowel extender can be a hydraulic and/or a shape memory alloy (SMA) actuated device.
Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.